298 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 13 



The most common of the salt marsh plants are Salicornia subterminalisj 

 Lepturus cylindricuSj Frankenia grandifolia, Heliotropium Curvassicum 

 oculatum, and Jaumea carnosa. 



Fresh water marshes and springy hillsides occur on all the islands 

 with the exception of those of volcanic origin. On Santa Barbara, San 

 Clemente, and Anacapa the lava forms no bedding planes and the water 

 is not carried out to the surface, except for small seepages near the water 

 level. Typha angustifolia is found on Santa Catalina, Santa Rosa, and 

 Santa Cruz. Anemopsis calif ornica grows on Santa Catalina, San 

 Miguel, San Nicolas, Santa Rosa, and Santa Cruz. Rorippa nasturtium- 

 aquaticum is on Santa Cruz and Santa Catalina, while Conium macula- 

 turn has been reported from these two islands and San Nicolas, and 

 Jussiaea califomicum as well as Scirpus californicus on Santa Cruz, 

 while Scirpus Olneyi occurs on San Nicolas and Santa Rosa. 



There are two veiy temporary small playa lakes, one on Santa 

 Catalina and one on San Miguel. These hold water for such short 

 periods that they probably contain no specialized vegetation, at least 

 none has yet been reported. 



Sand Dunes 



There are well developed sand dunes on San Clemente, San Nicolas, 

 and San Miguel, while embryonic dune areas, back of broad sand 

 beaches, occur on Santa Catalina. Franseria bipinnatifida, Abronia 

 maritima, and A triplex leucophylla are the most common and most 

 widespread of the dune plants. Abronia alba and Franseria chamissonis 

 occur on San Miguel, San Nicolas, and San Clemente. Cakile edentula 

 californica, Abronia latifolia, and Mesembryanthemum chilense are to 

 be found on San Miguel, the latter also on Anacapa. Platystemon cali- 

 fornicus ornithopus occurs on the sand dunes of both San Miguel and 

 San Nicolas. 



V Phytogeography of the Islands 



The problems of the affinities, origins and distributions of the plants 

 of the Channel Islands have been discussed and in some cases studied 

 by practically every botanist and geologist who has visited the islands. 

 Any attempt to understand these matters involves the interpretation of 

 past geological events and of the climatic changes which may have 

 affected this insular area. Some material for this understanding has 

 already been presented in previous sections of this paper and will be 

 intergrated here. Final solutions must await the accumulation of data 

 of greater extent. 



